To move the folder to /usr/share/themes, you would have to do it as an administrator, using sudo or gksudo from the command line, depending on how you wish to move the folder. You would have full permission to make a folder called .themes in your home folder without any resort to the command line.

You can then set the permissions on the folder by right clicking on the folder within your file manager, selecting Properties and then selecting the Permissions tab to make sure you have read, write & execute rights in the folder.